Definition of a shield feature for additive manufacture

Abstract

There is disclosed additive manufacturing apparatus comprising: a controller (110) to: receive object data relating to an object to be generated; and define print data for additive manufacture of the object by ejection of a print agent on build material in a pattern corresponding to selective fusing of the build material, wherein the print data is defined based on the object data so that the pattern defines a shield feature (56) embedded within the object to inhibit fusing of build material corresponding to the shield feature relative build material corresponding to an adjacent portion of the object; and a print agent distributor (104) to eject a print agent on build material based on the print data.

The invention claimed is: 
     
       1. Additive manufacturing apparatus comprising:
 a controller to:
 receive object data relating to an object to be generated; 
 define print data for additive manufacture of the object by ejection of a print agent on build material in a pattern corresponding to selective fusing of the build material, wherein the print data is defined based on the object data so that the pattern defines a shield feature embedded within the object to inhibit fusing of build material corresponding to the shield feature relative build material corresponding to an adjacent portion of the object; and 
 
 a print agent distributor to eject a print agent on build material based on the print data. 
 
     
     
       2. Additive manufacturing apparatus according to  claim 1 , wherein the controller is to:
 determine a surface feature of the object to be generated based on the object data received; and 
 define the print data based on the surface feature so that a profile of the shield feature corresponds to a profile of a surface of the object and is spaced from the surface of the object by a shell feature. 
 
     
     
       3. Additive manufacturing apparatus according to  claim 1 , wherein the controller is to define the print data to inhibit fusing of build material corresponding to the shield feature relative to build material corresponding to a core of the object adjacent to the shield feature. 
     
     
       4. Additive manufacturing apparatus according to  claim 3 , further comprising a radiation source, and wherein the controller is to define the print data to inhibit fusing of build material corresponding to the shield feature in response to radiant heat from the radiation source, relative to build material corresponding to the core of the object. 
     
     
       5. Additive manufacturing apparatus according to  claim 4 , wherein the print agent distributor is to eject a print agent which is a fusing agent, and wherein the controller is to:
 cause the radiation source to apply a predetermined amount of radiant heat to a layer of build material; and 
 define the print data so that build material corresponding to the shield feature has a concentration of fusing agent below a threshold concentration, and so that build material corresponding to the core of the object has a concentration of fusing agent at or above the threshold concentration; 
 wherein the threshold concentration is set so that build material having a concentration of fusing agent at or above the threshold concentration fuses in response to the predetermined amount of radiant heat. 
 
     
     
       6. Additive manufacturing apparatus according to  claim 5 , wherein the controller is to define the print data so that, in use as radiant heat is transferred to the build material, heat transfer from build material corresponding to the core causes build material corresponding to the shield feature to fuse. 
     
     
       7. Additive manufacturing apparatus according to  claim 1 , wherein the print agent distributor is to eject a print agent which is a fusing agent, and wherein the controller is to:
 define the print data so that no fusing agent is applied onto build material corresponding to the shield feature; and so that fusing agent is applied onto build material corresponding to the adjacent portion of the object. 
 
     
     
       8. Additive manufacturing apparatus according to  claim 1 , wherein the controller is to:
 control the print agent distributor to eject the print agent on each of a plurality of successive layers of build material based on the print data to generate respective slices of the object; and 
 define the print data for each layer of build material to eject the print agent in a respective pattern defining:
 a slice boundary corresponding to an outer surface of the object; 
 a shield region within the slice boundary and corresponding to the shield feature; 
 a shell region extending from one side of the shield region and terminating at the slice boundary; and 
 a core region disposed inside of the shield region. 
 
 
     
     
       9. Additive manufacturing apparatus according to  claim 1 , wherein the controller is to:
 receive object data corresponding to a plurality of slices of the object to be generated; and 
 wherein for each respective slice, the controller is to:
 analyse the object data to determine a virtual boundary of the slice; 
 define a virtual shield region within the virtual boundary, so that there is a virtual shell region extending from the virtual shield region and terminating at the virtual slice boundary; and 
 define the print data for the slice so that the respective pattern defines a shield region corresponding to the virtual shield region, to inhibit fusing of build material corresponding to the shield region relative to build material corresponding to an adjacent region of the slice. 
 
 
     
     
       10. Additive manufacturing apparatus according to  claim 9 , wherein the controller is to:
 analyse the object data to determine a location of a stack-wise boundary at which the extent of the object along the stack direction terminates; and 
 define the virtual shield region of at least one slice based on the location of the stack-wise boundary, so that the virtual shield defines a shield feature offset from the stack-wise boundary. 
 
     
     
       11. A non-transitory machine-readable storage medium encoded with instructions executable by a processor and comprising instructions to:
 receive object data corresponding to a three-dimensional object; 
 define a virtual shield feature embedded within the object; and 
 define print data for additive manufacture of the object by the ejection of a print agent on build material in a pattern corresponding to selective fusing of the build material, wherein the print data is defined so that the pattern defines a shield feature corresponding to the virtual shield feature to inhibit fusing of build material corresponding to the shield feature. 
 
     
     
       12. A non-transitory machine-readable storage medium according to  claim 11 , wherein the instructions to receive object data are to receive object data corresponding to a plurality of slices of the object; and
 wherein, for each respective slice, the instructions to define the virtual shield feature are to:
 analyse the object data to determine a virtual boundary of the slice corresponding to a surface of the object; and 
 define a virtual shield region within the virtual boundary, so that there is a virtual shell region extending from one side of the virtual shield region and terminating at the virtual slice boundary, and a virtual core region disposed on the other side of the virtual shield region; and 
 
 wherein the instructions to define the print data are to define the print data so that, for each slice, the respective pattern defines a shield region corresponding to a respective virtual shield region. 
 
     
     
       13. A non-transitory machine-readable storage medium according to  claim 12 , wherein the instructions to define the virtual shield feature are to:
 analyse the object data to determine a location of a stack-wise boundary at which the extent of the object along the stack direction terminates; and 
 define the shield region of at least one slice based on the location of the stack-wise boundary, so that an object manufactured according to the print data includes a shield feature offset from the stack-wise boundary along the stack direction. 
 
     
     
       14. A method comprising:
 controlling a print agent distributor of an additive manufacturing apparatus to eject a print agent onto build material; 
 wherein the print agent distributor is controlled based on print data so that the print agent is ejected in a pattern defining a shield feature embedded within the object to inhibit fusing of build material corresponding to the shield feature relative to build material corresponding to an adjacent portion of the object; and 
 exposing the object zone to radiation so that radiant heat is transferred through the fusing agent to the build material to result in selective fusing of build material. 
 
     
     
       15. A method according to  claim 14 , further comprising:
 receiving object data relating to the object to be generated; 
 defining the print data based on the object data so that the pattern defines the shield feature. 
 
     
     
       16. The method of  claim 14 , further comprising, according to the pattern, distributing less of a fusing agent to a shield feature region of a layer of build material than to other regions of the layer of build material that are within the object being formed. 
     
     
       17. The method of  claim 14 , further comprising, according to the pattern, distributing a fusing reduction agent to a shield feature region of a layer of build material, the fusing reduction agent inhibiting fusion of the build material when exposed to fusing radiation. 
     
     
       18. The method of  claim 17 , wherein the fusing reduction agent is water. 
     
     
       19. The method of  claim 14 , further comprising, when heating the build material to form the object, using the shield feature as a heat sink to accept heat from a core region of the object that is surrounded by the shield feature, the shield feature being between the core region and an outer surface of the object being formed. 
     
     
       20. The method of  claim 14 , wherein the shield feature is at a uniform depth within and spaced from an outer surface of the object being formed.